First off, Japanese SFHs are on incredibly tiny lots compared to how zoning works in most American cities.

But the bigger issue with your argument here is that much more of Japanese residential land in major cities is used for multi-family housing than single-family. I'm not saying we should not allow single-family homes to exist. I'm saying zoning currently allocates far too much land exclusively for them. Tokyo is a pretty terrible counter-example for that.

It's the same thing with cars. Nothing wrong with driving, American cities just make them hyper-dominant rather than one option among several.